1. Field of the Invention
The present invention relates to a nitride semiconductor light emitting device comprising nitride semiconductor represented by a general formula InxAlyGa1-x-yN (0≦x≦1, 0≦y<1) and, more particularly, to a small-sized nitride semiconductor light emitting device having pad electrodes occupying a large proportion of the surface area provided for connection with an external circuit.
2. Description of the Related Art
In an ordinary nitride semiconductor light emitting device, at least an n-side nitride semiconductor layer and a p-side nitride semiconductor layer are formed on a substrate made of sapphire, SiC, GaN or the like, and current is supplied to flow from the p-side to the n-side semiconductor layer, thereby to emit light. Formed on the p-side nitride semiconductor layer is a p-side pad electrode to be connected with a positive lead of an external power supply by wire bonding or the like, and formed on the n-side nitride semiconductor layer is an n-side pad electrode to be connected with a negative lead of the external power supply. In case an insulating substrate such as sapphire is used, a part of the p-side nitride semiconductor layer is removed to expose the n-side nitride semiconductor layer whereon the n-side pad electrode is formed. In case an electrically conductive substrate such as SiC or GaN is used, the n-side pad electrode is formed directly on the back of the substrate.
In such a nitride semiconductor light emitting device as described above, it is a common practice to form a light transmitting electrode as a light emerging surface on the p-side nitride semiconductor layer so as to spread the current uniformly over the p-side nitride semiconductor layer (for example, Patent Document 1 or 2). The light transmitting electrode is formed over substantially the entire surface so as to spread the current to the entire p-side nitride semiconductor layer, and is formed from a light transmitting material such as thin metal film so as not to obstruct light.
[Patent Document 1] Japanese Unexamined Patent Publication (Kokai) No. 6-338632
[Patent Document 2] Japanese Unexamined Patent Publication (Kokai) No. 10-144962